A question about attire

I'm interviewing for an internship position with the State Attorney's Office, and I was wondering what the proper attire would be for the interview, and subsequently, if I get the position, the job itself. Full suit and tie too much? Suit without the jacket? Dress pants and dress shirt not enough? Lay it on me.

Good advice, gentlemen. My only concern was that, considering it's an unpaid internship and that I'm not in law school (yet), a full suit would be overkill. I can see that I was mistaken. I've heard "you should dress for the job you want, not the one you've got." I guess this applies.